Potential contribution of eucalypt harvest residues to soil organic carbon in Brazil
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Potential contribution of eucalypt harvest residues to soil organic carbon in Brazil Ivan F. Souza1,2 · Nairam F. Barros1 · Roberto F. Novais1 · Leonardus Vergütz1 · Ivo R. Silva1 Received: 15 February 2019 / Accepted: 19 December 2019 © Springer Nature B.V. 2020
Abstract The extent by which the contribution of eucalypt harvest residues (HR) to soil organic carbon (SOC) is impacted by soil disturbance during and/or after harvesting is unclear. We addressed this question by following the decomposition of HR in microplots (15-cm diameter, 15-cm height) and determining their contribution to SOC in 10 sites across southeastern Brazil. The experiment was set up according to a complete randomized block design arranged into a 3 × 2 factorial scheme including: HR removal (HR0), only bark removal (HR − B) and HR including bark (HR + B) applied to: undisturbed soil (US) with HR left on the soil surface or disturbed soil with HR mixed into the first 5 cm of the topsoil. We had eight blocks as replicates. Following a 12-month field decomposition, soil samples were fractionated to isolate SOC within the particle-size fractions (PSF) greater and lower than 53 µm. Subsequently, we used 13C to quantify the effects of the treatments in C3-derived SOC content (C3-SOC) within each PSF. For both PSF, their C3-SOC content increased in response to HR − B or HR + B relative to HR0, depending on soil disturbance and HR half-life time (t0.5). For HR − B, net increments in C3-SOC within the PSF > 53 µm 3-SOC increased significantly with HR t0.5, regardless of soil disturbance. Otherwise, the C content within the PSF
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